Gyro has been out for, what, 8 months? A year? He's been around for a long time. He's a new addition to DotA 2, but he has had a lot of time to get someone to "unlock his potential" in plain old DotA.
His problems:
His harassment tool is mediocre. Flak Cannons do mediocre damage over a relatively long period of time, during which the enemy hero has to both stay within the AoE and not go into fog. He has a unreliable stun that isn't worth the mana unless the enemy runs a fair distance, and if they do run, it will take a long time for the missile to reach them. They might be safe by that time. He has a missile salvo that will rip apart people who try to dive at him early game, but quickly lose a lot of power as the game drags on. His ultimate is good, but dodgable if you try to set it up within view of your target.
He also has severe problems with his squishyness. He has extremely low HP, and no reliable stuns or slows to get away when things get hairy until level 6, when he can waste his ultimate to get away.
His ultimate is good in combination with other AoE disables, sure, but as more heroes come out you will notice his ultimate is outclassed. Magnataur, for example, can chain in ~1000 damage with max level spells, along with a 4 second stun instead of a puny slow. Earthshaker already outclasses his ultimate.